#include<iostream>
#include<vector>
using namespace std;

class Solution {
public:
    int search(vector<int>& nums, int target) {
        int left = 0, right = nums.size();
        while (left < right) {
            int mid = (left + right) >> 1;
            if (nums[mid] < target)left = mid + 1;
            else if (nums[mid] > target)right = mid - 1;
            else return mid;
        }
        if (left < nums.size() && left >= 0) return nums[left] == target ? left : -1;
        else return -1;
    }
};